1. Field
Embodiments relate to a nonvolatile semiconductor memory device.
2. Description of the Related Art
A NAND type flash memory is known as a nonvolatile semiconductor memory device that is electrically rewritable and capable of a high degree of integration. A memory cell of the NAND type flash memory includes a charge accumulation layer formed on a semiconductor substrate via a tunnel insulating film, and a control gate stacked on the charge accumulation layer via an inter-gate insulating film. The memory cell stores data in a nonvolatile manner by a charge accumulation state of the charge accumulation layer.
Now, this NAND type flash memory includes NAND strings having the memory cells connected in series therein, and during a write operation to the memory cell, the NAND type flash memory is required to charge a body region of an unselected NAND string. However, when this charging prior to the write operation is not sufficiently performed, there is a risk that voltage application during the subsequent write operation causes an increase in erroneous write to the memory cell in the unselected NAND string.